1. Field of the Invention
The present invention relates to a front part body structure of a vehicle, and more particularly, to a joining structure of an upper frame.
2. Description of the Related Art
In many front part body structures of vehicles, an engine room is generally provided in front of a cabin. A front part of the vehicle containing the engine room is provided with front side members which are positioned at right and left sides in a lateral direction of the vehicle, a plurality of cross members which are bridged between the front side members, suspension support panels which are joined to the front side members, and upper frames which are fixed to front pillars constituting the cabin side, at their one ends. Upper parts of struts which function as input parts from a front suspension of a strut type to a vehicle body are respectively fixed to the right and left suspension support panels by means of bolts, thereby to form strut houses.
The upper frames which are positioned at the right and left sides in the lateral direction of the vehicle are extended in a longitudinal direction of the vehicle, and formed in a closed sectional structure having their respective inner panels joined and fixed to the strut houses, and their respective outer panels superposed on and joined to the inner panels. In each of the upper frames, one end of the outer panel is joined to the front pillar by arc welding, and thus, joining rigidity is secured. At the same time, the other end of the outer panel is connected to a radiator bracket and so on which are positioned at the front side of the vehicle. JP-A-2001-39338 discloses a joining structure of the upper frame of this type.
Although the upper frame in the related art is advantageous in that the rigidity can be obtained, because the upper frame is joined to the front pillar at its one end by arc welding, it is difficult to maintain quality such as positional accuracy. Moreover, an arc-welded part of the upper frame bears a load from the front suspension in a vertical direction of the vehicle, because the arc-welded part is positioned in a rear part of the vehicle than the strut house which functions as the input part from the front suspension to the vehicle body, and the upper frame itself is connected to the strut house. For this reason, in case where the rigidity of the upper frame against the load in the vertical direction of the vehicle is weak, steering performance may be badly affected. Therefore, for the purpose of enhancing driving feeling of the vehicle, it is necessary to secure the rigidity of the upper frame.